Cooling towers have been widely used in data center buildings, power stations, chemical plants, and other industries where cost effective and energy efficient cooling is needed. The sizes of the cooling towers vary from relatively small roof-top units to very large hyperboloid structures. In a data center building, a cooling tower may be placed on the roof top of the building to remove waste heat generated by servers and other communication and processing equipment in operation in the data center building.
A cooling tower extracts waste heat to the atmosphere through the evaporative cooling of a fluid stream to a lower temperature. The evaporative cooling allows a portion of the fluid stream to evaporate into a moving air stream to provide significant cooling to the rest of that fluid stream. The heat from the fluid stream transferred to the air stream raises the air stream's temperature and its relative humidity, and the warm and moist air is discharged to the atmosphere. As a result, the temperature of the fluid stream is lowered.
The cooled fluid stream is collected in a basin of the cooling tower and is circulated again to absorb the waste heat from the data center. The cooling tower may be connected to a chiller or a heat exchanger. The heat exchanger may use the cooled fluid stream to absorb the waste heat; the chiller may further cool the fluid stream before it is circulated to absorb the waste heat. The temperature of the fluid stream rises again after it absorbs the waste heat from the heat source. The fluid stream is then again evaporated into the moving air stream to provide cooling to the rest of the fluid stream.
The moving air stream enters the cooling tower through one or more air inlets on the lateral walls of the cooling tower. For some cooling towers, the air inlets may be located at the base of the cooling tower and may comprise one or more drift eliminators. The drift eliminator removes entrained fluid droplets from the air stream to limit the drift rate of the fluid dream to save the fluid so that it can be recirculated for a longer period of time. Air enters the cooling tower through the air inlets and travels upward to interact with the warm fluid stream; a small portion of the warm fluid stream is evaporated which removes the heat from the remaining fluid stream. In some cooling towers, the fluid stream comprises water and the air stream comprises natural air outside of the cooling tower. The cooling tower that uses water as the fluid stream are sometimes referred to as the water cooling tower.
To provide efficient cooling, one or more fans may be placed either at the air inlet of a cooling tower to force air into the tower or on the roof of the cooling tower to pull air through the cooling tower. To increase the surface interaction area between the air stream and the fluid stream, a medium called fill is often used in a cooling tower. A splash fill comprises materials such as plastics placed to interrupt the fluid stream causing splashing. A film fill comprise of sheets of material upon which the fluid streams; the sheets of material may be made of plastics or metal alloys. The fluid stream is splashed onto the fill and the fluid droplets resulting from the splash interact with the air stream; the evaporation of the fluid stream into the moving air stream provides cooling to the rest of the fluid stream.
When the fluid evaporates in a cooling tower, any mineral constituents are left behind. The buildup of these minerals must be controlled to prevent mineral fouling of the cooling towers. In general, chemicals (dispersants) may be added to the fluid to prevent the formation of mineral scale. However, minerals may still gradually build up inside the cooling tower. In particular, minerals may build up on the drift eliminators of the cooling tower. As a result, periodic cleaning (such as a bi-weekly cleaning) of the drift eliminators may be required. The periodic cleaning of the drift eliminators may be time consuming and costly. Reducing the frequency of the cleaning schedules for the drift eliminators reduces the maintenance time and cost of the cooling tower.